Imatinib Blood Level Testing – Current Perspectives and Key Questions

Abstract

Imatinib is the gold standard for the treatment of chronic myeloid leukaemia. Several recent studies have revealed a correlation between imatinib trough plasma levels and clinical response, suggesting that measurement of plasma levels can be a useful tool for optimising imatinib dose. However, a number of important questions on the use of imatinib blood level testing (BLT) remain unanswered. These questions were discussed at a European expert meeting held in Bordeaux, France, under the auspices of the European Treatment and Outcome Study (EUTOS) for chronic myeloid leukaemia. The key views were that: imatinib blood level measured between days seven and 29 of treatment could be a prognostic indicator and an important baseline for evaluating subsequent measurements; an imatinib trough plasma threshold for optimal response of 1,000ng/ml has been proposed but needs further validation; there is insufficient evidence to define any relationship between imatinib plasma levels and adverse events; and, although it is not yet possible to define and validate a comprehensive algorithm for the application of BLT in clinical practice, a working model has been developed. Pan-European collaboration, data pooling and initiation of a prospective clinical trial would be important steps in addressing current uncertainties.